Sulphur concentration, SPAD value and yield of Marandu grass as related to sulphur supply

Abstract

Sulphur (S) is an important macronutrient for plant metabolism and growth, being a component of aminoacids and other organic compounds. In Brazil, as a result of the constant use of concentrated NPK fertilizers, besides some edaphic and climatic factors, sulphur became a limiting nutrient for plant development. The objective of this study was to evaluate the productive and nutritional attributes of Brachiaria brizantha cv. Marandu when submitted to S rates in the nutrient solution (0, 2, 4, 16, 32, 48, 64 and 80 mg L^-1). The experiment was carried out in a greenhouse, using plastic pots containing grinded silicon as substrate, during the Spring-Summer season. The first harvest occurred at 42 days after transplanting, while the second, occurred at 41 days after the first one. At this time, the roots were separated from the substrate. S concentration in plant parts, total number of tillers, dry matter production of aerial parts and roots, as well as the chlorophyll meter readings (SPAD value) were influenced by S in both growth periods of the grass. Critical concentration in emergent leaves (EL) and recently expanded leaves (RL) were 0.50 g kg^-1 and 0.52 g kg^-1, in the second harvest, respectively. The critical SPAD values determined in the RL were 38.5 in the second harvest. The Marandu grass showed itself responsive to S supply showing up higher outputs with the increased applied rates.